<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        
        function myreserve(arr){
            // var arr=new Array();
            for(var i=0;i<arr.length/2;i++){
                var temp=arr[i]
                arr[i]=arr[arr.length-i-1]
                arr[arr.length-i-1]=temp
            }
            return arr
        }
        console.log(myreserve(["1","2","3","4","5"]))
        //[5,4,3,2,1]
    </script>
</body>
</html>